Separation of Ionic Compounds by Reversed-Phase Liquid Chromatography An Update of Ion-Pairing Techniques

Abstract

Reversed-phase separation systems have become the most popular mode of liquid chromatography because of the participation of the mobile phase in the equilibrium distribution of the sample molecules. Recent investigations have demonstrated that the retention of charged molecules on bonded phase packings due to the presence of appropriate ionic agents in the mobile phase is an attractive alternative to the ion-exchange mode. This article examines the use of ionic mobile phase modifiers for the retention of ionic compounds by reversed-phase liquid chromatography. The role of ion suppression and ion pairing is discussed with respect to current hypotheses and to the practical application of the technique. An expanded review of recent applications is included.